1. Field of the Invention
This invention relates to an exposure apparatus for producing an Ultra Large Scale Integrated Circuit (ULSI), a liquid crystal display panel and so on.
2. Description of the Related Art
X-ray exposure apparatus have been developed as an exposure apparatus to produce ultra large scale integrated circuits (ULSI). The X-ray exposure apparatus use X-rays from synchrotron orbital radiation (SOR) as an exposure source. By this kind of X-ray exposure, fine circuit patterns of a width not more than 0.2 .mu.m can be transformed to semiconductor wafers.
A conventional structure of such an X-ray exposure apparatus is shown in FIG. 1 and FIG. 2. FIG. 2 shows a plane view of the structure shown in FIG. 1.
Referring these Figures, on a wafer stage frame 11, a wafer table 13 is installed. The wafer table 13 comprises four stages. These are an X-stage 15, a Y-stage 17, a Z-stage 19 and .theta.-stage 21. The wafer table 13 has six degrees of freedom which are the X-direction, Y-direction, Z-direction and .theta.-rotation, consisting of .theta.x-rotation, .theta.y-rotation and .theta.z-rotation, with use of these stages respectively. In front of the wafer table 13, a wafer chuck plate 23 is attached, which can hold and release alternately an exposure target such as a semiconductor wafer 25 by vacuum chucking. On the other hand, a mask 27, in which circuit patterns are described, is connected to a mask frame 31 with a mask chuck plate 29. The mask 27 is placed against the semiconductor wafer 25 and held by the mask chuck plate 29 by vacuum chucking.
First the position of the semiconductor wafer 25 is moved in X-, Y-direction, .theta.x-, .theta.y- and .theta.z-rotation by the three stages, X-stage 15, Y-stage 17, .theta.-stage 21. Then the position of the semiconductor wafer 25 is adjusted with the Z-stage 19 to be close to the mask 27 and the gap g between the semiconductor wafer 25 and the mask 27 is fixed. The circuit patterns in the mask 27 are transferred on the semiconductor wafer 25 by the exposure of X-ray emission from SOR. The gap g would be in about 10 to 50 .mu.m.
When the semiconductor 25 is attached on or released from the wafer chuck plate 23, or when the mask 27 is attached on or released from the mask chuck plate 29, the wafer stage 11 is moved in the X-negative direction represented by an arrow 33 as shown in FIG. 3, and sufficient space between the wafer chuck plate 23 and mask chuck plate 29 is secured for the operation of attaching or releasing to be done. The wafer stage frame 11 is so heavy that it takes a long time to move from an exposure position to an attaching and releasing position. The apparatus including the moving means for this heavy stage frame should become a large-scaled apparatus.